Oh, thank you all so much! To make things more confusing though, I have since started wondering if the 7100 is worth the extra few hundred dollar difference (or at least that is about the price difference I'm showing)……So….thoughts on the 7100 to the 5300, now?? Again, my current is the D90 but thinking about selling it but I would have to sell it with the lens attached since I can not remove it for whatever reason. Thanks!
Depends on your type of shooting. If you're an "auto" shooter, only using a couple basic kit lenses, etc... Then the D5300 is all you really need. The image quality is virtually identical between the cameras. They likely use the same sensor, so really will produce the same images, when used in the same way.
The D7100 has a number of enhancements, most of which are designed for more advanced users. They are definitely worthwhile features for such users, but meaningless for some.
Among the enhancement everyone will notice: The D7100 has a much nicer viewfinder. If you held them side by side, you would notice the D7100 viewfinder is brighter and larger. If you looked at the D7100 first, and then held the D5300 to your eye, it would feel like a small dark tunnel. The D7100 also covers the entire image in the viewfinder, the D5300 cuts off the edges.
The next big difference is the level of manual controls. Both cameras let you take manual control. But the D7100 has far more buttons and dials, to make it easy for an advanced user to change every possible setting. For example, two control dials, so the advanced user can change both aperture and shutter speed at the same time. The D5300 lets you make manual adjustments, but you need to dive through more menus to do so. Thus, it's faster and easier to make manual adjustments on the D7100. For some users, this is a big deal. For others, pretty meaningless.
The D7100 has a more advanced autofocus system. But the D5300 isn't a slouch. Alone, it's not a reason to spend extra.
The D7100 has 2 media card slots, the D5300 only has 1. So if you want a "back up" memory card, or want to save RAW files on 1 card, and save JPEG files on another card, at the same time, the D7100 lets you do it.
The D7100 is weather sealed, the D5300 isn't. In practice, a few drops of rain isn't going to break the D5300. But if you want to use your camera in a hurricane or blizzard, you're better off with the D7100.
The D7100 has a much longer battery.
The D7100 can shoot at 1/8000 of a second, the D5300 is limited to 1/4000. This is irrelevant for 99% of shooters, 99% of the time... but if you want to shoot at 1.4 aperture, in the bright sunlight, then you need that 1/8000!
D7100 has 6fps vs 5 fps on the D5300.... But they both have poor buffers, so neither camera is a great sports shooter.
This is big for some people: The D7100 has an auto focus motor, enabling you to use every AF Nikon lens built in the last 50 years. The D5300 lacks the motor, so it can only use the newer Nikon lenses. Again, irrelevant if you are just using a couple newer kit lenses. Very relevant if you want to use some very old very good lenses, or some of the Nikon specialty lenses that still require a motor.
Those are the differences I can think of. You need to figure out if any of those differences are meaningful to you. I would go with the D7100, but I'm a pretty advanced shooter, and like having the extra manual controls, and the larger viewfinder.